Joshua A Bauer

• PhD
• Director of High-throughput Screening at Vanderbilt University

Genome-wide association studies have identified approximately 200 genetic risk loci for breast cancer, but the causal variants and target genes are mostly unknown. We sought to fine-map all known breast cancer risk loci using genome-wide association study data from 172,737 female breast cancer cases and 242,009 controls of African, Asian and Europe...

Background: Triple-negative breast cancers (TNBCs) typically have a greater immune cell infiltrate and are more likely to respond to immune checkpoint inhibition (ICI) than ER+ or HER2+ breast cancers. However, there is a crucial need to optimize combining chemotherapy strategies with ICI to enhance overall survival in TNBC. Methods: Therefore, we...

Triple-negative breast cancers (TNBC) typically have a greater immune cell infiltrate and are more likely to respond to immune checkpoint inhibition (ICI) than ER+ or HER2+ breast cancers. However, there is crucial need to optimize combining chemotherapy strategies with ICI to enhance overall survival TNBC. Therefore, we developed a high-throughput...

Development of an understanding of membrane nanodomains colloquially known as “lipid rafts” has been hindered by a lack of pharmacological tools to manipulate rafts and protein affinity for rafts. We screened 24,000 small molecules for modulators of the affinity of peripheral myelin protein 22 (PMP22) for rafts in giant plasma membrane vesicles (GP...

Vascular smooth muscle KATP channels critically regulate blood flow and blood pressure by modulating vascular tone and therefore represent attractive drug targets for treating several cardiovascular disorders. However, the lack of potent inhibitors that can selectively inhibit Kir6.1/SUR2B (vascular KATP) over Kir6.2/SUR1 (pancreatic KATP) has elud...

Glucose, a primary fuel source under homeostatic conditions, is transported into cells by membrane transporters such as glucose transporter 1 (GLUT1). Due to its essential role in maintaining energy homeostasis, dysregulation of GLUT1 expression and function can adversely affect many physiological processes in the body. This has implications in a w...

Antagonists of the serotonin receptor 2B (5-HT2B) have shown great promise as therapeutics for the treatment of pulmonary arterial hypertension, valvular heart disease, and related cardiopathies. Herein, we describe a high-throughput screen campaign that led to the identification of highly potent and selective 5-HT2B antagonists. Furthermore, selec...

Kir6.2/SUR1 is an ATP-regulated potassium channel that acts as an intracellular metabolic sensor, controlling insulin and appetite-stimulatory neuropeptides secretion. In this Letter, we present the SAR around a novel Kir6.2/SUR1 channel opener scaffold derived from an HTS screening campaign. New series of compounds with tractable SAR trends and fa...

To fertilize an oocyte, the membrane potential of both mouse and human sperm must hyperpolarize (become more negative inside). Determining the molecular mechanisms underlying this hyperpolarization is vital for developing new contraceptive methods and detecting causes of idiopathic male infertility. In mouse sperm, hyperpolarization is caused by ac...

Aim Deregulated signaling pathways are a hallmark feature of oncogenesis and driver of tumor progression. Dual specificity protein phosphatase 4 (DUSP4) is a critical negative regulator of the mitogen-activated protein kinase (MAPK) pathway and is often deleted or epigenetically silenced in tumors. DUSP4 alterations lead to hyperactivation of MAPK...

A high-throughput cell-based screen identified redox-active small molecules that produce a period lengthening of the circadian rhythm. The strongest period lengthening phenotype was induced by a phenazine carboxamide (VU661). Comparison to two isomeric benzquinoline carboxamides (VU673 and VU164) shows the activity is associated with the redox modu...

Simple Summary There are currently few treatment options for individuals diagnosed with anaplastic thyroid carcinoma (ATC). Using four distinct ATC cell lines, we screened over 1500 anti-cancer agents and FDA-approved drugs. The initial screen and secondary confirmation testing identified 40 agents of interest for further evaluation. Validation was...

Heteromeric Kir4.1/Kir5.1 (KCNJ10/KCNJ16) inward rectifier potassium (Kir) channels play key roles in the brain and kidney, but pharmacological tools for probing their physiology and therapeutic potential have not been developed. Here we report the discovery, in a high-throughput screen of 80,475 compounds, of the moderately potent and selective in...

Plasma membrane organization profoundly impacts cellular functionality. A well-known mechanism underlying this organization is through nanoscopic clustering of distinct lipids and proteins in membrane rafts. Despite their physiological importance, rafts remain a difficult-to-study aspect of membrane organization, in part because of the paucity of c...

We have previously identified a genetic variant, rs34331122 in the 22q11.21 locus, as being associated with breast cancer risk in a genome-wide association study. This novel variant is located in the intronic region of the T-box transcription factor 1 (TBX1) gene. Cis-expression quantitative trait loci analysis showed that expression of TBX1 was re...

Simple Summary Previous research has revealed a genetic predisposition to breast carcinogenesis. Thus, identifying causal genetic variants and their associated gene networks may improve breast cancer diagnostics and risk assessment. Our study investigated YBEY, an uncharacterized gene in humans, and its functions in breast cancer risk and progressi...

Generation of fine-needle aspiration (FNA)-derived cancer organoids has allowed us to develop a number of downstream applications. In this protocol, we start with organoids cultured in a semi-solid format. We dissociate organoids into single cells and then plate in a 384-well format for high-throughput drug screening. While this method must be fine...

We have previously identified SNP rs3541811, located in the 21q22.3 locus, to be associated with breast cancer risk in Asians. However, the underlying causal functional variants and gene(s) responsible for this association are unknown. In this study, we performed functional genomic analyses to identify potential functional variants and target genes...

We have previously identified a genetic variant, rs34331122 in the 22q11.21 locus, to be associated with breast cancer risk in genome-wide association studies. This SNP is located in the intronic region of the T-box transcription factor 1 () gene. is a member of the T-box transcription factor gene family, which plays important roles in embryogenesi...

Patient-derived cancer organoids hold great potential to accurately model and predict therapeutic responses. Efficient organoid isolation methods that minimize post-collection manipulation of tissues would improve adaptability, accuracy, and applicability to both experimental and real-time clinical settings. Here we present a simple and minimally i...

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer that does not respond to endocrine therapy or human epidermal growth factor receptor 2 (HER2)–targeted therapies. Individuals with TNBC experience higher rates of relapse and shorter overall survival compared to patients with receptor-positive breast cancer subtypes. Precli...

Thyroid cancer has the fastest growing incidence of any cancer in the United States, as measured by the number of new cases per year. Despite advances in tissue culture techniques, a robust model for thyroid cancer spheroid culture has yet to be developed. Using eight established thyroid cancer cell lines, we created an efficient and cost-effective...

The treatment of tumors driven by overexpression or amplification of MYC oncogenes remains a significant challenge in drug discovery. Here, we present a new strategy towards the inhibition of MYC via the disruption of the protein-protein-interaction between MYC and its chromatin cofactor WDR5. Blocking the association of these proteins is hypothesi...

INTRODUCTION: Oncogenic mutations in EGFR are found in 15-30% of non-small cell lung cancers (NSCLC). Patients with EGFR-mutant NSCLC derive clinical benefit from EGFR tyrosine kinase inhibitors (TKIs), such as erlotinib and afatinib. Recently, a 3rd-generation EGFR TKI, osimertinib, was approved for first-line treatment of metastatic EGFR-mutant N...

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers in the world. Genome-wide association studies have identified approximately 50 genetic risk loci for CRC. We have previously identified SNP rs7229639, located in the second intronic region of the SMAD7 gene at locus 18q21.1, in relation to CRC risk in Asians. In this study, we pe...

Genome-wide association study–identified prostate cancer risk variants explain only a relatively small fraction of its familial relative risk, and the genes responsible for many of these identified associations remain unknown. To discover novel prostate cancer genetic loci and possible causal genes at previously identified risk loci, we performed a...

Genome-wide association study–identified prostate cancer risk variants explain only a relatively small fraction of its familial relative risk, and the genes responsible for many of these identified associations remain unknown. To discover novel prostate cancer genetic loci and possible causal genes at previously identified risk loci, we performed a...

Using an ORF kinome screen in MCF-7 cells treated with the CDK4/6 inhibitor ribociclib plus fulvestrant, we identified FGFR1 as a mechanism of drug resistance. FGFR1-amplified/ER+ breast cancer cells and MCF-7 cells transduced with FGFR1 were resistant to fulvestrant ± ribociclib or palbociclib. This resistance was abrogated by treatment with the F...

Two goals motivate treating diseases with drug combinations: reduce off-target toxicity by minimizing doses (synergistic potency) and improve outcomes by escalating effect (synergistic efficacy). Established drug synergy frameworks obscure such distinction, failing to harness the potential of modern chemical libraries. We therefore developed multi-...

The mitotic spindle is a microtubule-based machine that segregates a replicated set of chromosomes during cell division. Many cancer drugs alter or disrupt the microtubules that form the mitotic spindle. Microtubule-dependent molecular motors that function during mitosis are logical alternative mitotic targets for drug development. Eg5 (Kinesin-5)...

Viruses are molecular machines sustained through a life cycle that requires replication within host cells. Throughout the infectious cycle, viral and cellular components interact to advance the multistep process required to produce progeny virions. Despite progress made in understanding the virus-host protein interactome, much remains to be discove...

In the rapidly expanding landscape of quantitative systems pharmacology and personalized medicine, identifying synergistic drug combinations is of paramount interest. Synergistic drugs have the potential to increase the efficacy of the current therapeutic pool at reduced doses, ameliorating off‐target toxicities. However, current methods to quantif...

Background: CDK4/6 inhibitors have been approved in combination with endocrine therapy for treatment of ER+ metastatic breast cancer. The goal of this study was to discover mechanisms of resistance to ER antagonists alone and in combination with CDK4/6 inhibitors. Results: To achieve this goal, we used lentiviral vectors to individually express 559...

The CDK4/6 inhibitor palbociclib was recently approved in combination with endocrine therapy for treatment of ER+ metastatic breast cancer. The goal of this study was to discover mechanisms of resistance to ER antagonists alone and in combination with CDK4/6 inhibitors. To achieve this goal, we used lentiviral vectors to individually express 559 hu...

Mutant-selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI), such as osimertinib, are active agents for the treatment of EGFR-mutant lung cancer. Specifically, these agents can overcome the effects of the T790M mutation, which mediates resistance to first and second-generation EGFR TKI, and recent clinical trials have...

To discover mechanisms of resistance to CDK4/6 inhibitors, we used a kinome-wide siRNA screen to identify kinases that, when downregulated, promote sensitivity to ribociclib. We identified 3-phosphoinositide dependent protein kinase 1 (PDK1) as the top siRNA that sensitized ER+ MCF-7 cells to ribociclib. Pharmacological inhibition of PDK1 with GSK2...

Unlabelled: Chikungunya virus (CHIKV) is a reemerging alphavirus that has caused epidemics of fever, arthralgia, and rash worldwide. There are currently no licensed vaccines or antiviral therapies available for the prevention or treatment of CHIKV disease. We conducted a high-throughput, chemical compound screen that identified digoxin, a cardiac...

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Digoxin inhibits the production of progeny virions from CHIKV RNA-electroporated cells. U-2 OS cells were incubated with DMSO, 10 µM 5-NT, or digoxin at the concentrations shown for 1 h prior to electroporation with CHIKV SL15649 RNA generated in vitro. Cells were incubated in complete medium (left) or medium containing DMSO or inhibitor (right). A...

Activation of NF-κB following digoxin treatment. U-2 OS cells were transfected with pGL4-3XκB, which expresses firefly luciferase under control of NF-κB, and the control pRL-SV40 plasmid, which constitutively expresses Renilla luciferase. At 24 h posttransfection, cells were either adsorbed with CHIKV strain 181/25 at an MOI of 10 PFU/cell for 1 h...

CHIKV attachment to cells is not impaired following digoxin treatment. U-2 OS cells were incubated with DMSO, 10 µM 5-NT, or digoxin at the concentrations shown for 1 h prior to adsorption with CHIKV strain 181/25 at an MOI of 100 PFU/cell at 4°C for 1 h. Unbound virus was removed, cells were stained with CHIKV-specific antiserum, and virus-bound c...

Sequences of primers used for detection of human and murine sodium-potassium ATPase subunit transcripts.

Background: Dysregulation in cell cycle checkpoints is common in cancer. Small molecule inhibitors that target the CDK4/6/cyclinD1 pathway of the cell cycle are in clinical development. Recently the combination of the CDK4/6 inhibitor palbociclib and the aromatase inhibitor letrozole was approved for the treatment of post-menopausal women with ER+/...

Estrogen receptor-positive (ER+) breast cancer is the most common clinical subtype of breast cancer. Endocrine therapies that target ER signaling have significantly reduced mortality in patients with ER+ breast cancer. Fulvestrant is a selective ER downregulator currently approved for treatment of patients with advanced hormone-dependent breast can...

New epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) that are targeted against EGFR T790M, such as AZD9291, are among the most promising agents for the treatment of EGFR mutant lung adenocarcinomas, as they can overcome a key mechanism of acquired resistance to first or second generation EGFR-TKIs. Emerging clinical data in...

Background: Small molecule inhibitors that target the CDK4/6/cyclinD1 pathway are in clinical development. Clinical trials combining the CDK4/6 inhibitor pallbociclib and the aromatase inhibitor letrozole have demonstrated significantly improved clinical outcomes in patients with ER-positive breast cancer. This combination is likely to be approved...

Manganese (Mn) is both an essential biological cofactor and neurotoxicant. Disruption of Mn biology in the basal ganglia has been implicated in the pathogenesis of neurodegenerative disorders, such as parkinsonism and Huntington's disease. Handling of other essential metals (e.g. iron and zinc) occurs via complex intracellular signaling networks th...

Introduction: Triple negative breast cancer (TNBC) is a heterogeneous collection of biologically diverse cancers, which contributes to variable clinical outcomes. Previously, we identified a TNBC subtype that has a luminal phenotype and expresses the androgen receptor (AR+). TNBC cells derived from these luminal AR + tumors have high frequency pho...

Unlabelled: Neoadjuvant chemotherapy (NAC) induces a pathologic complete response (pCR) in approximately 30% of patients with triple-negative breast cancers (TNBC). In patients lacking a pCR, NAC selects a subpopulation of chemotherapy-resistant tumor cells. To understand the molecular underpinnings driving treatment-resistant TNBCs, we performed...

Apoptosis is irreversible programmed cell death, characterized by a cellular cascade activation of caspase 3, which subsequently degrades proteins and other components of cells with a motif sequence. Here we report a novel reporter system to detect apoptosis, growth arrest, and cell death based on controlled and self-amplified protein degradation....

Exome sequencing using next-generation sequencing technologies is a cost-efficient approach to selectively sequencing coding regions of the human genome for detection of disease variants. One of the lesser known yet important applications of exome sequencing data is to identify copy number variation (CNV). There have been many exome CNV tools devel...

Background High-throughput RNA interference (RNAi) screens have been used to find genes that, when silenced, result in sensitivity to certain chemotherapy drugs. Researchers therefore can further identify drug-sensitive targets and novel drug combinations that sensitize cancer cells to chemotherapeutic drugs. Considerable uncertainty exists about t...

Triple negative breast cancers (TNBC) are generally more aggressive than other types of breast cancer, with higher rates of relapse in the early stage and decreased overall survival in the metastatic setting. TNBC has been particularly difficult to treat given that the biology of the disease is not well understood, and until recently, molecular tar...

Motivation: Triple-negative breast cancer (TNBC) is a heterogeneous breast cancer group, and identification of molecular subtypes is essential for understanding the biological characteristics and clinical behaviors of TNBC as well as for developing personalized treatments. Based on 3,247 gene expression profiles from 21 breast cancer data sets, we...

Triple negative breast cancers (TNBCs), that are hormone receptor negative (estrogen and progesterone) and lack HER2 amplification have limited treatment options. There is increasing evidence that TNBC is a heterogeneous disease and that patients with TNBC differentially respond to standard chemotherapies, which in many cases predicts for outcome....

Triple-negative breast cancer (TNBC) is a highly diverse group of cancers, and subtyping is necessary to better identify molecular-based therapies. In this study, we analyzed gene expression (GE) profiles from 21 breast cancer data sets and identified 587 TNBC cases. Cluster analysis identified 6 TNBC subtypes displaying unique GE and ontologies, i...

Background: Currently, there are targeted therapies for estrogen receptor (ER) positive and HER2-amplified breast cancers. However, treatment options for patients with triple negative breast cancers (TNBCs), tumors that are hormone receptor negative (ER and progesterone, PR) and lack HER2 amplification, has been limited by the heterogeneity and lac...

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Triple negative breast cancers (TNBCs) are characterized by the absence of estrogen/progesterone receptors and HER2 gene amplifications. Patients with TNBC have a poor prognosis and cannot be effectively treated with current targeted therapies. Our overall goal is to identify...

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Purpose: A prospective trial of preoperative concurrent paclitaxel and radiation for patients with LABC was conducted at three academic institutions. Five-year local and systemic control rates are reported. Patients and Methods: 105 patients with LABC were treated with...

We have previously demonstrated high pathologic response rates after neoadjuvant concurrent chemoradiation in patients with locally advanced breast cancer (LABC). We now report disease-free survival (DFS) and overall survival (OS) in the context of pathologic response. 105 LABC patients (White 46%, Non-White 54%) were treated with paclitaxel (30 mg...

Growth conditions of breast cancer cell lines. Cell culturing conditions for panel of triple-negative breast cancer cell lines.

Knockdown of PPM1D expression correlates with increased paclitaxel sensitivity in breast cancer cells. A. Non-silencing (NS) control, four individually designed PPM1D-1 (P1 to P4) or pooled PPM1D siRNAs (Dharmacon ON-TARGET plus) were transfected into MCF-7 and MDA-MB-468 cells. Cells were harvested 72 h after transfection, RNA purified, and the re...

Paclitaxel is a widely used drug in the treatment of patients with locally advanced and metastatic breast cancer. However, only a small portion of patients have a complete response to paclitaxel-based chemotherapy, and many patients are resistant. Strategies that increase sensitivity and limit resistance to paclitaxel would be of clinical use, espe...

567 Background: Prospective trials of preoperative concurrent paclitaxel (P) and radiation (RT) for LABC were conducted at three academic institutions. Rates of pathologic response, DFS and OS are reported. Methods: 105 LABC patients were treated between March 1997 and August 2009; 33 at University of Southern California, 36 at New York University...

To identify molecular markers of pathologic response to neoadjuvant paclitaxel/radiation treatment, protein and gene expression profiling were done on pretreatment biopsies. Patients with high-risk, operable breast cancer were treated with three cycles of paclitaxel followed by concurrent paclitaxel/radiation. Tumor tissue from pretreatment biopsie...

To prospectively identify markers of response to therapy and outcome in an organ-sparing trial for advanced oropharyngeal cancer. Pretreatment biopsies were examined for expression of epidermal growth factor receptor (EGFR), p16, Bcl-xL, and p53 as well as for p53 mutation. These markers were assessed for association with high-risk human papillomav...

MDM2 oncoprotein binds directly to the p53 tumor suppressor and inhibits its function in cancers retaining wild-type p53. Blocking this interaction using small molecules is a promising approach to reactivate p53 function and is being pursued as a new anticancer strategy. The spiro-oxindole MI-43, a small-molecule inhibitor of the MDM2-p53 interacti...

We showed that tumor cells with wild-type p53 and high levels of Bcl-x(L) are cisplatin resistant but are induced to undergo apoptosis by (-)-gossypol, making this a promising agent for overcoming cisplatin resistance. However, some cells in a population with this phenotype are not killed and continue to survive. Conversely, tumor cells with low Bc...

Cisplatin resistance remains a barrier to organ-sparing and survival of patients with advanced head and neck squamous cell carcinoma (HNSCC). Targeted therapies to overcome cisplatin-resistant HNSCC are being developed. Cisplatin-sensitive parental HNSCC cell lines and cisplatin-resistant progeny were studied. Pretreatment HNSCC biopsies were used...

The RAS/BRAF/MEK/ERK mitogen-activated protein kinase (MAPK) pathway is emerging as a key modulator of melanoma initiation and progression. However, a variety of clinical studies indicate that inhibiting the MAPK pathway is insufficient per se to effectively kill melanoma cells. Here, we report on a genetic and pharmacologic approach to identify su...

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Objective To study the role of the inhibitor of apoptosis protein (IAP), survivin, in cisplatin-induced head and neck squamous cell carcinoma (HNSCC) cell death. Design Parental and cisplatin-resistant HNSCC cells were evaluated for expression of survivin. The HNSCC cells were then transduced with lentiviral small interfering RNA (siRNA) expressio...

Objective: To determine the contribution of reactive oxygen species (ROS) in (−)-gossypol-induced cell death in head and neck squamous cell carcinoma (HNSCC) cell lines.Design: The HNSCC cell lines were treated with (−)-gossypol, and generation of ROS was measured by fluorescence microscopy and flow cytometry. Cells were treated with (−)-gossypol a...

Objective To understand the role of p53 in head and neck squamous cell carcinoma (HNSCC) cells in response to cisplatin treatment. Design The HNSCC cells that contain mutant (nonfunctional) p53 and high levels of the prosurvival protein Bcl-xL were transduced with wild-type (WT) p53, and HNSCC cells containing WT p53, also overexpressing Bcl-xL, w...

Objective To evaluate the role of CD24 expression regarding cisplatin sensitivity in head and neck squamous cell carcinoma (HNSCC) cell lines. Design Cell line study involving University of Michigan Squamous Cell Carcinoma (UM-SCC) cell lines. Main Outcome Measures Expression of membrane-bound CD24 was measured by flow cytometry in molecules of e...

Organ preservation protocols in head and neck squamous cell carcinoma (HNSCC) are limited by tumors that fail to respond. We observed that larynx preservation and response to chemotherapy is significantly associated with p53 overexpression, and that most HNSCC cell lines with mutant p53 are more sensitive to cisplatin than those with wild-type p53....

Bcl-xL overexpression is common in head and neck squamous cell carcinomas (HNSCC) and correlates with resistance to chemotherapy. Thus, a nonpeptidic, cell-permeable small molecule that mimics the BH3 domain of proapoptotic proteins may inhibit Bcl-xL function and have therapeutic potential for HNSCC by overcoming drug-resistance. (-)-Gossypol, the...

Vitamin D has been suggested as a chemopreventive and therapeutic modality for prostate cancer. However, hypercalcemic toxicity has limited the use of 1alpha,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) in clinical trials, prompting the search for analogs of vitamin D with less toxicity while retaining efficacy as a modality for cancer intervention....